1. Field of the Invention
The present invention generally relates to a polymer nanocomposite. More particularly, the invention relates to a polymer nanocomposite formed from a mixture of a clay dispersion with a polymer dispersion.
2. Description of the Relevant Art
There has been considerable interest in forming nanocomposites especially by addition of clay minerals into polymeric materials. Clay minerals such as montmorillonite are composed of silicate layers with a thickness of about 1 nanometer.
Incorporation of such layered materials in polymers result in products which may frequently be referred to as nanocomposites. Incorporating clay minerals in a polymer matrix, however, may not always be a straightforward process. Incorporating clay minerals may require additional manufacturing steps or additional capital equipment costs, especially if melt processing may be required. Some have tried to improve the process of forming nanocomposites by increasing the compatibility between the clay minerals and the organic polymers. Thus, it has been proposed to use lipophilic compounds, such as onium compounds, to treat the clay minerals to increase the compatibility of the clay minerals in a polymer as shown in U.S. Pat. No. 4,889,885, to Usuki et al. and U.S. Pat. No. 4,810,734 to Kawasumi et al, both of which are incorporated herein by reference.
Another proposed method to improve incorporation of clay minerals into polymers is the use of emulsion polymerization. A dispersion is produced having a layered silicate, a monomer, and a polymerization initiator. The monomer is polymerized to form the latex. This polymerization process results in a latex containing a layered material intercalated with a polymer. This method is disclosed in U.S. Pat. No. 5,883,173 to Elspass et al., which is incorporated herein by reference. However, the approaches to preparing nanocomposites, whether by melt processing, ionic additions, or emulsion polymerization, may prove difficult in controlling exfoliation and polymer molecular weight. Efficiency in emulsion polymerization may also be difficult to achieve.